How to change CloudWatch metrics_collection_interval for ECS

Metrics_collection_interval – Optional. Specifies how often all metrics specified in this configuration file are to be collected. You can override this value for specific types of metrics. This value is specified in seconds. For example, specifying 10 causes metrics to be collected every 10 seconds, and setting it to 300 specifies metrics to be collected every 5 minutes. If you set this value below 60 seconds, each metric is collected as a high-resolution metric. The default value is 60.

The following is an example of an agent section. You can modify the interval from 60 to the desired value (in seconds).

"agent": {
   "metrics_collection_interval": 60,
   "region": "us-west-1",
   "logfile": "/opt/aws/amazon-cloudwatch-agent/logs/amazon-cloudwatch-agent.log",
   "debug": false,
   "run_as_user": "cwagent"
  }

Not sure you can specify this agent parameter from terraform. You can check this part of the documentation for further details.